This invention relates to an improved irrigation system and, more particularly, to an improved apparatus for sequentially irrigating a plurality of areas or basins, automatically stopping the flow of water to an area when that area has received sufficient irrigation and redirecting the flow of water to another area.
Irrigation systems have been used for many years to provide plants and trees with water at various times during their growing cycle. For example, it has been common practice to provide plants and trees with water by means of irrigation ditches, hoses, sprayers, pipes and other types of apparatus. However, in certain situations, such as in orchards where the terrain is uneven, water will run from the high ground to the low. In such cases, the low lying trees may receive more water than those on higher ground.
In other cases, where the cost of water is relatively high it is desirable to control the amount of water provided for each area and to avoid wasting water by providing additional water to some plants in order to adequately water others or by leaving the water on for too long a period.
The above problems have been overcome to a degree by irrigation systems having a plurality of valves with each valve connected by means of pipes to a pressurized source of water. For example, the U.S. Pat. Nos. of Rodieck, 3,797,253 and 4,014,361, disclose systems wherein each item to be watered is provided with a well around its base and a separate valve within each of the wells. In such systems, one or more risers may be provided in order to force each valve that has been closed by the water reaching a preselected height in the well and to remain closed for as long as there is water pressure applied to the system. Such systems also include means to prevent the flow of water to a second valve until such time that a first area has been provided with a predetermined volume of water.
A more recent development is disclosed in my co-pending application entitled "Irrigation System," Ser. No. 07/457,870, which was filed on Dec. 27, 1989, and which is incorporated herein in its entirety by reference. As disclosed therein, an irrigation system includes one or more valve assemblies which are connected in series to a pressurized source of water. Each valve assembly includes a cylindrical housing, a ball valve, an inlet and two outlets with one outlet generally opposite from the inlet in a lower portion of the housing. The other outlet is disposed in an upper portion of the housing and is adapted to direct water to an area of ground for irrigation. A pit and a float are associated with each valve assembly and arranged so that some of the irrigation water will flow into the pit and raise the float. The float is connected to spring biasing means and when the float reaches a predetermined level, the ball valve will spring upwardly to close the upper outlet and redirect the water to another assembly. Water pressure will then maintain the valve in that position.
The present invention contemplates an improved system of the type which is disclosed in my aforementioned application. For example, in the aforementioned system, the pressure resulting from the flow of water creates friction between a ball and seat (outlet). Thus, as the water pressure is increased, the force which is required to move the ball upwardly out of contact with a first seat and into contact with the second seat increases. Consequently, it is necessary for the float to rise up to a higher level to activate the change. In other words, the prior art devices may be sensitive to changes in water pressure and increase or decrease the amount of water applied to an area in response to a change in water pressure.
It is presently believed that an improved irrigation system as disclosed and claimed herein provides for a more accurate determination of the amount of water to be delivered to a given area. Also, the amount of water delivered is independent of any changes in water pressure. In addition, the system disclosed herein is reliable in operation, minimizes the likelihood that a gate member will become stuck in a first position and thus fail to turn off a valve and will have a more rapid trigger action. It is also believed that the system disclosed herein may be readily and economically manufactured, relatively free of maintenance and simple to operate.